1. Field of the Invention
The invention relates to a battery-type determination apparatus, a battery-type determination method, and an electronic apparatus for determining a type of a battery.
2. Description of the Related Art
Batteries are conventionally used as driving power supplies for a variety of electronic apparatuses. Batteries are classified into a plurality of types, e.g., dry cells of manganese batteries and alkaline batteries, and rechargeable nickel hydride batteries. These types of batteries have respectively different battery lifetimes and discharging properties. For example, the battery lifetimes are longest in the order from manganese batteries, alkaline batteries, and nickel hydride batteries. With respect to a drop property from the start of a voltage drop, both of the manganese and alkaline batteries show gentle voltage drops, while the nickel hydride batteries show a comparatively steep drop.
Therefore, for example, an electronic dictionary, a calculator, a touchpanel-type personal digital assistant (PDA), which are electronic apparatuses each operated by a CPU driven with a rated voltage, need to set different voltage values (or thresholds) for warning consumption of battery due to reduction in remaining battery power, depending on types of batteries, for example, by setting a higher voltage value for use of hydrogen batteries than use of alkaline batteries.
Conventionally, an electronic apparatus which allows use of a plurality of types of batteries has a function to allow a user to select/set and store a battery type. Depending on battery types stored, setting voltage values are switched to issue warnings as mentioned above concerning consumption of battery.
In a conventional remaining-battery determination apparatus, voltage drop amounts of battery voltages without load and under maximum load are compared with thresholds for determining battery types, to thereby determine a battery type. Further consideration is taken into determination on whether battery power remains or not by comparison with a threshold for determining remaining battery power (for example, Jpn. Pat. Appln. KOKAI Publication No. 2008-003022).
An apparatus has been designed which detects a battery type by determining a battery type, based on a difference between a current value flowing during driving of an electronic apparatus and a current value flowing during not driving of the electronic apparatus (for example, refer to Jpn. Pat. Appln. KOKAI Publication No. 11-250942).
Among electronic apparatuses which allow use of a plurality of types of batteries, there is an electronic apparatus which allows a user to select and set a battery type. The electronic apparatus not only requires the user to set a battery type repeatedly each time a battery is replaced with a different type of battery, but also possibly causes a problem in warning consumption of battery due to a setting error.
In a method of determining a battery type by a conventional remaining-battery-power determination apparatus or a battery-type detection apparatus, an amount of voltage drop and a difference in current values are greatly influenced by an amount of remaining battery. Therefore, particularly when an amount of remaining battery is small, there is a problem that a determination error easily occurs.
Under the circumstances, it is desired to provide a battery-type determination apparatus, a battery-type determination method, and an electronic apparatus including the battery-type determination apparatus, which are capable of distinguishing battery types.